Graphene cryogels synthesis is reported by amine modification of carboxylated graphene oxide via aqueous carbodiimide chemistry. The effect of the amine type on the formation of the cryogels and their properties is presented. In this respect, ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), were selected. The obtained cryogels were characterized by Fourier Transformed Infrared spectroscopy, thermogravimetric analysis, X-ray spectroscopy, and Scanning electron microscopy. The CO₂ adsorption performance was evaluated as a function of amine modification. The results showed the best CO₂ adsorption performance was exhibited by ethylenediamine modified aerogel, reaching 2 mmol g⁻¹ at 1 bar and 298 K. While the total N content of the cryogels increased with increasing amine groups, the nitrogen configuration and contributions were determined to have more important influence on the adsorption properties. It is also revealed that the residual oxygen functionalities in the obtained cryogels represent another paramount factor to take into account for improving the CO₂ capture properties of amine-modified graphene oxide (GO)-based cryogels.

Low-density three-dimensional (3D) N-doped graphene aerogels by a one-step solvothermal method in the presence of ethylenediamine (EDA) are reported. The gelation, formation, and properties of the aerogels were studied with solvothermal conditions, namely, operating temperature, time, graphene oxide (GO) concentration, and the GO/EDA w/w ratio. Two ranges of solvothermal conditions are employed: one involving an operating temperature below 100 °C and a conventional chemical reduction of GO with EDA at atmospheric pressure and a second one employing a higher temperature range up to 165 and a high pressure reduction with EDA. The results show that both solvothermal approaches allow for the fabrication of homogeneous N-doped 3D graphene aerogels with density values close to 10 mg cm⁻³. The measurements indicated that low values of GO concentration, temperature, and EDA are optimum for obtaining low-density 3D aerogels. N doping is improved with an EDA amount in lower temperature conditions. The N doping mechanism below 100 °C is dominated by the epoxy ring opening while at temperatures up to 165 °C both epoxy ring opening and amidation take place. The CO₂ adsorption properties are strongly controlled by the nitrogen configuration, namely, pyridinic nitrogen in terms of its density.

Ultra-light eco-friendly graphene oxide (GO)-based aerogels are reported by simple one-step solvothermal self-assembly. The effect of varying parameters such as C/O ratio of GO; reducing agent amount; temperature; and duration on the properties of the aerogels was studied. The structural and vibrational features and hydrophobic surface properties of the obtained aerogels were obtained by XRD; FTIR; XPS; Raman; SEM; and contact angle measurements. The effect of synthesis conditions on the engine oil and organic solvent absorption properties was assessed. The results indicated that the lower the C/O ratio of GO, the better the absorption properties, with the best performance for oil uptake reaching 86 g g⁻¹. The obtained results indicate the approach based on ice-templating and the tailoring of oxygen content in GO make the resulting aerogels potential candidates for use in oil spill and organic solvent treatments.